Conventionally, when direct mails and billing statements including an address and a name are disposed, a leakage of personal information to the third person is suppressed by the use of a paper shredder or a security stamp. In particular, security stamps are inexpensive in comparison with paper shredders, and enable concealing of personal information by just stamping on the written portion of the personal information. Accordingly, security stamps are convenient for standard home having no paper shredder.
For example, Unexamined Japanese Patent Application KOKAI Publication No. 2009-255515 discloses a stamping device which puts and presses a stamping device main body against the personal information part of a printed object, thereby imprinting fixed alphabets, KANJI (Chinese characters), numbers, and symbols, etc., in order to conceal personal information. Moreover, Unexamined Japanese Patent Application KOKAI Publication No. 2010-17881 discloses a roller-type stamping device that imprints fixed characters, such as KANJI, HIRAGANA, and numbers often used for address by allowing a stamping device main body to be pushed against the personal information part of a printed object and moved so as to trace the personal information part, thereby concealing personal information.
According to Unexamined Japanese Patent Applications KOKAI Publications Nos. 2009-255515 and 2010-17881, however, respective stamping devices are for pressing a print face including predetermined alphabets, KANJI, numbers, and symbols, etc., and the contents of the print face are fixed, so that various character strings to be concealed and indicating personal information, such as an address, a name and a telephone number are concealed by stamping of the print face that is always same. Accordingly, the concealing effect is insufficient in some cases, and personal information may be read.